Color images may be captured and reproduced by a variety of digital devices, such as digital cameras and digital recorders. In capturing an image, to collect raw information representing the image, a digital device may use various optical lenses, sensors and filters. However, due to a range of factors, such as physical limitations of the optical lenses and sensors, a raw image captured by a digital device often suffers from problems such as chromatic aberration, lack of clarity, insufficient contrast in fine detail areas, inadequate sharpness, etc. To correct the problems, the captured image is often digitally processed. After the raw image data is processed, the resulting image is rendered and delivered to a user.
Techniques for digital processing of the captured images allow for reducing the image distortion, enhancing image contrast and sharpness, enhancing detail definition in fine detail areas, etc. One of the techniques often applied to raw image data is image sharpening. Sharpening is typically used to enhance sharpness and contrast in various portions of an image.
However, one of the problems with the current sharpening techniques is that the techniques have a tendency to produce image artifacts, such as over-sharpening of edge-areas and introducing noise in fine-detail areas. For example, sharpening of some images may cause the appearance of the edges to be over-exaggerated and the details in the fine-detail areas to be deemphasized, unclear or fuzzy. For instance, while processing an image of a parcel box, the current sharpening techniques often exaggerate an appearance of the edges of the parcel box, but deemphasize the details of the fine print depicted on the parcel's label. The resulting image may look unacceptable because it may be difficult to read the fine print on the parcel's label. Thus, in general, the current image processing techniques, including the current sharpening techniques, fail to provide results that are wholly satisfactory.